


It was only a kiss ( It was only a kiss.)

by 2kitsune



Category: Undertale (Video Game)
Genre: (kind of), Ecto-Genitalia, Ecto-Penis, Ecto-Tongue, F/M, Frisk has breasts & a vagina but no gender is specified, Hand Jobs, Implied Sexual Content, Kissing, Making Out, Masturbation, Motorboating, Other, Sans is still very much male, Sensitive bones, Sexual Content, Swearing, Voyeurism, humping
Language: English
Status: Completed
Published: 2016-04-17
Updated: 2016-04-17
Packaged: 2018-06-02 19:12:08
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 2,691
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6578959
Author URL: https://archiveofourown.org/users/2kitsune/pseuds/2kitsune
Summary: <blockquote class="userstuff">
              <p>It's not Sans's fault that he's clumsy, nor is it his fault that he happens to fall right onto Frisk when they're hanging out. However this accident has a happy ending - it's just a shame it was interrupted by a very annoying brother.</p>
            </blockquote>





	It was only a kiss ( It was only a kiss.)

**Author's Note:**

> So I recently got into Undertale and fucking fell for it hard. I ended up being a 'part' of the fandom before I even started playing the game, thanks to a friend, but I did eventually buy it. Of course I immediately fell in love with Sans. This fic can also easily be changed to a sans x reader fic, but I liked the idea of him with Frisk better. 
> 
> I did age Frisk up in this fic, seeing as she's young in the games. Imagine she's at the legal age of your country, thanks :)

Today day had been long and boring and Sans was ready to curl up in his bed and sleep for a thousand years. He doesn’t bother calling out to Papyrus as he unlocks the front door, pushing it open and then slamming it shut with his foot once he had crossed over the threshold, knowing that the taller skeleton liked to go see Undyne once Papyrus had finished his own work.

 

Toeing off his shoes Sans then shoved his feet into his slippers, sighing at the immediate comfort it brings. However, when he looks up he lets out a startled shout as his eyes land on a familiar shape on their couch, nearly jumping from fright but at least managing not to and keeping a shred of his dignity.

 

The figure on the couch lets out a muffled shout against the sleeve of their shirt, eyes crinkling in laughter. It’s Frisk, of course it was, but what they were doing here was a mystery to Sans – not that they weren’t welcome, but Sans would like to know beforehand.

 

“Smooth,” Frisk comments. “Did I rattle your bones?”

 

Sans deadpans. “Ha, ha, very _punny_ ,” He comments as he shakes his head, but still slowly shuffles over to the couch where Frisk is lounging. They’ve taking up most of the couch in blankets, TV on in the background but on mute now that Sans was hear and honestly the skeleton doesn’t know how he didn’t hear that as he opened the door, alerting him to someone else’s presence in the house other than his own.

 

“I’ve taught you well, kid.”

 

Frisk’s eyes light up, a smile stretching across their lips. “Do you want to join me?” They ask. “I was thinking about watching some anime. You could make popcorn?” Asks Frisk, hopefulness creeping into their tone that Sans grinned at. He was a master at making popcorn, and everyone around knew it.

 

Sans pretends to think about it. “Hmmmm,” He eventually hums. “I mean I guess I could, as long as you let me pick the anime as well. I don’t want a repeat of the anime Undyne snuck in last time, I had nightmares for a week.” Sans says, shivering at the memory.

 

“Deal!” Frisk agrees, getting comfortable once again on the couch because they had shifted a little to talk to Sans properly. The skeleton rolls his eyes, reaches out to muse up their hair which earns him a yell and a slap to his Humerus. It doesn’t hurt, not really, but Sans fakes pain more for the fun of it, before moving into the kitchen.

 

The popcorn is unwrapped and then put into the microwave, Sans mouth hanging open a little as he keys in the time needed. In the lounge he can hear that Frisk has unmuted the TV again, and the sound of Mettaton’s voice floats into the kitchen.Sans pushes off of the counter when the microwave beeps, pulling out the popcorn and depositing it into a bowl. He takes a couple of pieces before taking it out, crumpling up the discarded wrapped and making a shot towards the trash can, grinning widely to himself when it hits the rim but still goes in never- the- less.

 

It’s only a brief trip to the coffee table where Sans places the popcorn, shooting a smirk at Frisk before turning to pick an anime. There are still a lot that they hadn’t gotten through when Undyne was here last with Alphys, so Sans picks at random and puts it into the CD player.

 

Frisk pulls up their feet when Sans moves to sit on the couch, but just as he was about to turn to sit, his foot caught on something and the sound that left his mouth was very undignified as he started falling. Frisk shouted too at some point, but Sans was too busy desperately trying to reach out and grab something to stop himself from falling but he was coming in very fast to Frisks chest.

 

There was nothing he could do. Sans lands, face first, into a warm chest that jiggles under his impact. He lays there for what feels like hours, although it was probably on seconds, with his heartbeat pounding in his ears, his mouth surprisingly dry considering he was a Skeleton.

 

'Oh, _fuck_.' Thinks Sans. 

 

“Uhhh Sans?” Frisk eventually asks, so quietly that Sans nearly doesn’t hear them but oh god he can fucking feel the vibrations of their speech through their chest. It’s not something he’s felt before, he’s never fallen face first into someone’s’ breasts before either, and it makes his cheeks flush blue.

 

“Are you just gonna’ stay there?”

 

Sans, finally getting control of himself again, reels back, but doesn’t get up from his half- crouched- over position on top of Frisk. They’re face to face now, a little too close to be platonic, breaths faintly washing over each other and suddenly Sans feels far too hot in his hoodie.

 

“I’m-“ Starts Sans, cheeks still faintly blue. He knows he needs to apologize, but that’s easier said than done. Refusing to meet Frisk’s eyes he continues, instead settling for a space to their right. “ _Shit_ , I didn’t mean to do that – _fuck_ , sorry, I’ll – uhhh.”

 

Frisk starts flushing too, a small smile on their lips. “Dude, it’s okay,” they murmur. “It was an accident, right?”

 

Sans nods. “Fuck- yeah, it was totally an accident. I didn’t mean to - jump your bones,” He trails off lamely, trying to cover his embarrassment with a thinly veiled joke. Thankfully, thank fucking god, Frisk finds it funny and lets out a little snort of laughter.

 

And fuck, it’s cute. It’s far too fucking cute. Up close Frisk is surprisingly more adorable than Sans had originally thought, with a pretty button nose and petal pink lips, a small dusting of freckles across their cheeks. He’s hit with the overwhelming urge to do – something. But what?

 

 “Are you- “ Frisk slowly starts, and when Sans finally meets their eyes they’re looking at him almost expectantly. “Are you going to get off?”

 

Huh? Sans blinks, eyes flicking between Frisk and then down between them. He does that a couple of times, god he’s so fucking _slow_ , before he realizes that he’s still fucking on them and Frisk had asked him quite a bit ago if he was going to get off of them.

 

“Fuck – right, _I_ -“ Sans starts, finally starting to move. But it was obvious the world just hated him today, because he didn’t get to climb off of Frisk very far before he misjudges where the couch cushion was in relation to his phalanges and slips again.

 

He doesn’t fall face first into their breasts again. ‘Small mercies,’ Sans thinks. But he does fall far too close to Frisk’s face, close enough that he can see himself in their pupils, close enough that their foreheads touch and there’s only a split fucking second where Sans gets to draw in a shaky breath before Frisk rolls their eyes and leans in to kiss him.

 

There’s not much to kiss, but just the simple act of pressing their lips against his teeth is fucking enough and Sans curls into them, curls into their warmth and drinks it in. Frisk smells beyond good, smells of warmth and comfort, and Sans’s hands tighten into the couch cushions.  

 

The blanket over Frisk’s lap and legs gets stuck between the couch and Sans Patella’s when he shifts, pressing further into them. Slowly, as though not to frighten him, and Sans briefly entertains himself in that thought, Frisk presses their lips to his more firmly, Frisk brings one clench into his hoodie, the fur mattered under their fingers, and the other comes up to cup Sans’ mandible.

 

Monsters don’t tend to touch other monsters much, tending to prefer their own personal space over anything else, so Sans was not ready for the sensation that came from Frisk touching his mandible. He’s sensitive, almost overly sensitive, and wherever Frisk’s fingers brush tingles follow, enough to make Sans moan.His moans urge Frisk on, and they make a small sound back. Slowly, ever so fucking slowly because Sans has never kissed a human before, and in return Frisk has never kissed a monster before, the kiss becomes lewder and Sans can feel his magic gathering in his mouth, his chest, and another place he doesn’t necessarily want attention drawn to right now.

 

Now, as to not scare Frisk, he lets his magic pool, forming a blue tongue in his mouth that glows slightly. For a second he just keeps kissing Frisk, letting them pull him so that he’s now laying on then, before pushing his tongue out from between his lips.

 

And Frisk is less surprised than Sans thought they would be. Sure they start a little, pull back a little, gasp a little, but once Frisk realizes what’s going on they eagerly lean back in, tentatively opening their mouth to allow Sans’s tongue in. He gently recuperates, licking across Frisk’s lips and his soul throbs, shining through his white shirt, when he realizes they’re not going to push him away, smiling to himself at the eager sound that Frisk makes.

 

When Frisk opens their mouth and lets him in a rush of euphoria rushes through Sans’s bones. He slowly pushes between their lips, ducking down to lick along the inner of Frisk’s bottom lip before surging forwards and twisting their tongues together. The sound Frisk makes is enough to make his soul throb again, and Sans doesn’t have to look to know it was probably glowing through his shirt by now. He should stop, he really should, before they took this too far – but oh _god_ , Frisk just felt so fucking _good_ underneath him.

 

By accident, or not, Sans hips do eventually drop, dragging his pelvis shallowly against their own. It’s enough to make both of them stop in their tracks and Sans pulls away from the kiss, instead pushing his face into Frisk’s neck, making them hastily remove the hand that was still on Sans’s mandible, instead throwing it over his shoulder.

 

Sans pants against Frisk’s neck, tongue flicking out to taste the salty skin offered to him. There’s sweat on his skull, permanent blue on his cheeks, and he’s far too fucking hot as he rocks his hips again, moaning needily against Frisk’s neck. Frisk copies the action, rutting back up against his pelvis, although Sans doubts they’d receive any pleasure from it.

 

"Oh _fuck_." Mutters Sans under his breath. 

 

He manages to keep going but he’s too hot, and not far enough gone that he can’t leave it. Groaning he pulls back, sitting on Frisk’s lap, femurs straddling Frisk’s hips, and removes his hoodie as fast as he can. Sans nearly fucking yells when it gets stuck on his carpels, instead a feral growl escaping his mouth, but then Frisk reaches up and helps and he’s free, his hoodie thrown onto the ground.

 

Frisk re-initiates the kiss. They were a quick learner, sliding their tongue over Sans in a way that makes the skeleton melt, but Frisk’s hands flick up Sans’s shirt to plant themselves on his pelvis, stopping him from looming over them again.

 

“Hold up.” Frisk murmurs and in the same movement a hand drops, brushing against his ecto- dick through his basketball shorts and fuck- Sans nearly loses it right there and then. Frisk takes their time, and Sans feels like putty in their hands, but at least keep control of the kisses, pushing and pulling till Frisk’s hand stills on his crotch and moans in desperation and frustration at Sans’s skillful tonguing.

 

Rutting against their hand Sans was 69% he wasn’t going to last much longer. It had been a long time since he had been touched by someone else, he had no one but his own hand on those lonely nights where he can’t sleep and there are too many thoughts in his head, and even Frisk’s touch, never mind the slight fumbling, was more than enough.

 

Frisk obviously remembers what they had been doing, because their hand starts moving again with determination. More pressure is added as Frisk palms at his crotch, Sans whimpering when their fingertips brush over the head of his dick, and they start moving up to his waistband, fingers pushing just underneath and Sans whimpers, whines, fucking arches his hips forwards because he’s so fucking _desperate_ to be touched at this point when –

 

“SANS! I, THE GREAT PAPYRUS, IS HOME!”

 

The door flies open with such velocity that it bangs against the wall, Sans would look later and see that there was now an indention in the wall. Sans looks up so fast he hears his cervical vertebrae crack, however Frisk doesn’t turn, the human just drops their head into their hands, and Sans can see that Frisk’s whole face is red as well as their ears.

 

“I’VE BEEN AT UNDYNES WATCHING ANIME, BUT NOW I AM – Oh.”

 

That was the exact moment he sees Sans and Frisk in their compromising position on the couch. Papyrus’s eye sockets widen drastically, and his mouth falls wide open as he stares, sweat forming on his skull as he looks over the two on the couch and realizes, slowly, just exactly what was about to go down.

 

Sans’s gaze keeps flickering from Papyrus to Frisk, silently having a conversation with the latter. When the door had first banged open Frisk’s hand had immediately retreated from Sans’s crotch, and Sans had put a stopper on his magic which made his tongue and dick disappear, leaving only the slightly glowing stain in his crotch and the glowing from his chest cavity, from between his ribs. 

 

“I uh-“ Papyrus finally starts, stuttering over his words as his eyes shift between the door and the two of them. “I forgot something at Undynes – I’ll be back later.” With that he disappears, well it seems like he does. Papyrus turns and sprints back out of the house, and thankfully grabs the door behind him, leaving the two in the near darkness again.

In the silence Frisk and Sans meet eyes, bodies completely still. It’s Sans who breaks first, a smile slowly breaking out on skull, and Frisk quickly follows. Soon they’re both laughing, both at themselves and this stupid fucking situation, until Sans leans in again and presses his teeth to her lips.

 

“The anime,” Sans starts slowly, he had taken a look a bit ago to see the credits rolling. “Has ended, so we should probably rewind and watch what he we missed.”

 

“But,” Frisk starts, although he eyes are still twinkling. “We missed all of it.”

 

“Exactly,” Sans winks, at which Frisk just rolls their eyes. Slowly the skeleton crawls off of them, letting out a long sigh and stretching a little once he’s standing on his own two feet again. It’s then when he remembers the stain in his pants, and his blush returns.

 

“I should – uh, go change. Be right back?” Says Sans, voicing it like a question. Frisk looks like they’re going to laugh again, mirth showing in their expression, but the human nods and waves their hand in Sans’s general direction, telling him without speaking that he can go do what he needs to do. 

 

Sans doesn’t bother walking up the stairs, he was lazily at soul, and instead teleports. Suddenly he’s surrounded by the familiar walls of his room, a clutter of clothes and other shit on the floor, with the wood of his door against his vertebrae and his phalanges. His soul in still pounding, but it's starting to glow less now that it was being stimulated by anything, and Sans absently reaches up to place a hand over it, as though he could hide it. 

 

He ducks his head when his brain starts replaying what had happened moments before. Sans sighs under his breath as he remembers Frisk’s lips under his teeth, Sans’s cheeks flush blue when he remembers the humans’ needy moans, and Sans’s own hand wanders southwards as he remembers the feeling of Frisk’s hand on his crotch.

**Author's Note:**

> Thank you for reading this fic! please leave a KUDOS and a COMMENT, I really appreciate it!! Thanks! :)


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